Hydrogen fluoride alkylation process



Nov. 13, 1945. J. o. lvERsoN HYDROGEN FLUORIDE-ALKYLATION PROCESS Filed July 30, 1941 lNvENToR JoHN o. lvEsoN Patented Nov. 13, 194e HYDROGEN FLUORIDE ALKYILATION PROCESS John 0. Iverson, Chicago, El., assigner to Univeri .sal Oil Products Company, Chicago, Ill., a corporation oi' Delaware Application July 30, 1941,.S1crial No'. 404,607

6 Claims.L (Cl. 26o-683.4)

lThis invention relates to an improved process for the reaction of isoparailins with olelns in the presence of a hydrogen fluoride catalyst and is more particularly concerned .with a combination of related and cooperative steps whereby the process may be operated moreefficiently.

' The reaction of isoparaflins with oleflns in the presence of hydrogen iiuoride -as a catalyst has been heretofore proposed as a method of producing a Valuable motor fuel of high antiknock value, suitable -for aviation engines and as a blending agent to increase the antiknock rating of other motor fuels. In previously known processes. for reacting `isoparaiins with olens, a liquid mixture of isoparains and olens was agitated tgether with liquid hydrogen fluoride until the reaction was complete, and the resultant mixture was then allowed to settle in order to separate the hydrocarbon product from the hydrogen uoride. Heretofore, no adequate provision was made for reactivating or recovering the catalyst in a continuous manner. In this invention, several steps have been included for recovering and reactlvating the hydrogen fluoride catalyst which will materially reduce the ycost of the catalyst for the process and for therefore highly desirable from a commercial viewpoint.

One speciiic embodiment of the present invention comprises a process for reacting isobutane with butylenes which includes charging a normally gaseous feed containing isobutane and butylenes together with recycled isobutane, under sumcient pressure to maintain them in the liquid phase, to a reaction zone, wherein the hydrocarbons are intimately mixed with a liquid hydrogen iiuoride catalyst at an alkylating temperature for a time suilcient to complete the reaction between the isoparains and oleiins and form an emulsion l vapor from a redux condensate, condensing and returning the hydrogen uoride to the reaction zone, subjecting said reflux condensate to a second fractionation `in order to remove an isobutane fraction from a 4second reux condensate, returning said isobutane traction to the reaction. zone, further fractionating and treating-said second redux condensate to produce a high octanemotor fuel, continuously -lwithdrawing from the reaction zone a stream of used hydrogen fluoride catalyst, separately fractionating said used hy- -drogen iiuoride to remove purified hydrogen uoride vapors and any light hydrocarbons overhead froma third reiiux condensate comprising essentially polymers, and withdrawing said third reflux condensate, subjecting a Dor-tion of the purilied hydrogen iluoride to a still further fractional fluoride. In order to remove the hydrogen uoride A distillation whereby to separate relatively dry hydrogen fluoride as a vaporous product and a mixture of water and hydrogen fluoride as reflux condensate, and condensing and returning the puriv iled 'and dried hydrogen uoride to the reaction Zone.

car-bons. Therefore, the products from'the reaction zone will contain a small amount of the order of 1% of dissolved hydrogen fluoride. The fractionation step following the reaction zone is operated so as to remove any propane or other light gases present land also the dissolved hydrogen which has a higher boiling point than either butane or propane, it is necessary to vaporize a relatively large quantity of hydrocarbons. If no propane is to be removed'from the reaction products, the hydrogen uoride may be removed by Vaporizing, condensing, and refiuxing higher boiling hydrocarbons. This step of removing and recovering the dissolved hydrogen fluoride from the product is important because itspresence in the iinished product would present a serious corrosion problem and possible health hazard and would increase the amount oi catalyst that would have to be added to the process.

The hydrogen uoride catalyst tends to lose a. substantial proportionv of its activity after a period of use. This decrease in activity is mainly due to two factors, namely, the contamination of the hydrogen uoride with organic material and the dilution with water. Although it is not known whether the nature of the contamination drganic material containing hydrocarbon polymers remains after the distillation.

Hydrogen uoride has a-greater ainity for water and it is very diicult to remove water from the catalyst-by any ordinary dehydratingmethods. Although the incoming charge may be very nearly dry. nevertheless, the catalyst will gradu- Hydrogen uoride is slightly 'soluble in hydropasses through line l tier l1, wherein hydrogen ally accumulate water. This'water not only reduces the catalystactivity, but also makes the hydrogen fluoride more corrosive to the apparatus in which it is handled. It is desirable to' maintain the concentration of water in the hydrogen iluoride below about In the process of this invention, the water is removed from the catalyst in a fractionation step in which substantially dry hydrogen fluoride is distilled oiand a mixture or hydrogen fluoride and water is withdrawn as reux condensate. This mixture may be a constant boiling mixture containing about 35 to 40% of hydrogen fluoride' or some other mixture of higher hydrogen fluoride content.

Any suitable apparatus or reactor may be employed to contact the hydrocarbon reactants with the liquid catalyst in the reaction zone. It is only essential that very intimate contact between the two liquids be maintained for a period of time sumcient for the reaction. In general, some form of agitation, such as mixing, stirring, etc., is used,

.which forms a'n intimate mixture or emulsion of hydrocarbon and hydrogen fluoride. In one particular form of apparatus illustrated in the drawing, this agitation is obtained by continuously recycling a large portion 'of the reactants inthe time tank through an external 'coolerV and causing this emulsion to pass through rather small openings in a series of horizontal plates placed in the time tank whereby intimate contact is maintained between the hydrogen fluoride and hydrocarbon phases. A stream of fresh reactants is continuously added to the recirculating emulsion and a portion of the reaction products is continuously withdrawn from the recirculating emulsion. A settling section is provided in the time tank above the outlet to the recirculationline where most of the hydrogen fluoride in the portion ofthe withdrawn reaction 'products can l0 settle back into the recirculating stream. This settling section may eliminate the necessity for an outsi ie settler as it ispossible to remove all oi the residual hydrogen duoride carried over with the reaction products in the propane re, moval fractionating column.

The accompanying diagrammatic drawing illustrates one specific form of apparatus embodying the features of thev invention` and in which the process of the invention may be conducted.

Referring to the drawing, a normally gaseous charge consisting essentially of isobutane, butylenes, and butane is passed as a. liquid under pressure through line l, valve 2,-and charge pump I to line 4. A The charge iscombined in line 4 with a recycled isobutane fraction from line 5|. tThe combined iced from line l is then admitted to line Il containing a recirculating emulsion of hydrogen fluoride and hydrocarbons. The resultant commingled mixture is then-passed pump 6, line 1 and valve B to time tank 9,in which the interaction of oleilnlc and isoparalilnic hydrocarbons is substantially completed. A large portion of the emulsion of `hydrocarbons and hydrogen iluorde fromtime tank 9 is withdrawn through line Ill andvalve Il, through cooler l2,v wherein a portion of the heat of reaction is removed and thence through line I3 and valve I4 into lrecirculating pump I. The combination of tionator 24 is described. -A stream and valve I9 as shown later. The hydrocarbon from alkylation settler l1 passes through line 26,

valve 2l, pump 22, and' line 23 to fractionator 2li.'

The vapors from fractionator 24 pass through line 2'5 and valve 26, condenser 21, and valve 28 to receiver 29. This fractionation column removes the propane and dissolvedhydrogen uoride from the product. However, it is necessary to reux a large amount of hydrocarbon in order to remove all of the dissolved hydrogen uoride- This reid-ux is returned from receiver 29 through line Atitl, valve 3|, pump 32, and valve 33 to the upper portion 'of riractionator `26. Any gaseous propane that may be present is removed through line 3l and valve 35.- The hydrogen fluoride which separates as a heavy lower layer in the bottom of receiver 29 will be withdrawn through line 35 and valve 31 to be returned to the process as shown later. The reux condensate from frac- "thdrawn through line 38 and valve 39 and directedto a second fractionation step in ractionator sil. From this fractionation the overhead product, consisting mainly of isobutane, is withdrawn through line Si, valve d2, condenser 43 and valve 44 to receiver Q5. Any non-condensable gases present will be removed through line 46 and valve 41. The liquid isobutano passes through line 48, valve 69, pump Eil, line 5l, and valve 52 'to the beginning of the process where it is combined with the charge in line 4. A product consisting of n-butane and In order to maintain the catalyst activity in the reaction system, a small portion of the catalyst is continuously reactivated as hereinafter of hydrocarbon and hydrogen fluoride emulsion is Withdrawn from emule sion circulating line 1 through line` 53 and valve an emulsion settler 55, wherein the hydrogen uoride settles out. The hydrocarbon layer substantially freed from hydrogen uoride is returned to the reaction zone through line 56 and 5 valve 51. Hydrogen iluoride catalyst containing -throushline 6l and valve organic .contaminating materials is passed from emulsion settler 55 through line 58 and valve 58 toV fractionator -60 wherein a separation is eieeted into a purined hydrogen uoride fraction,

taken overhead through line 6l and valve 62, condenser 63 and valve 64 to receiver 65 equipped with conventional gas release, line 68 and valve B1; and ahydr'ocarbon fraction, consisting essentiallyof heavy drawn from the bottom of fractionator 60 69. A small amount of light hydrocarbons may also be carried overhead with the hydrogen iluoride. The puriiled liquid hydrogen uoride in receiver 85- is withdrawn through line 1l and valve 1I and is then divided into two streams, the one passing through line 10,to fractionator 12, and the other passing through line 13 and valve 1I to be recycled to the alkylation stage of the process as will be described later.

In fractionator 12, any water that is present in the hydrogen uoride is removed in the reflux condensate as a constant boiling mixture of time tank 9 with the emulsion recirculating sys- 70 water and hydrogen uorlde through vline 15 and valve 16. Dry hydrogen iluoride is withdrawn overhead `from fractionator 12 through line 11,

valve 18, condenser 19- and valve 80 to receiver l. Provision is made for the removal of any non-condensable gases from this receiver through line a2 and valve 83.".'The purified and dried alkylate is withdrawn through line 9| and valvel polymers, the latter being wit liquid hydrogen fluoride passes through line 8 5. valve 85, pump 86v andpvalve 81 to be returned to the reaction zone. The combined streams of hydrogen fluoride from lines 34, 86, I8, and 'I3 are returned through line 38 and line 58 to line I3 and the reaction zone. Fresh hydrogen fluoride catalyst may be added when necessary stance, the reactivation of the hydrogen fluoride catalyst may be carried out in a slightly different form of apparatus not shown in the drawlng. The used hydrogen` uoride catalyst which has been separated from the hydrocarbon phase is subjected to fractional distillation in a first fractionating column operated under suitable conditionsl to separate relatively dry hydrogen uoride and some normally gaseous hydrocarbons overhead from a reflux condensate which will consist o! a hydrogen fluoride-water mixture containing a higher percentage of water than the charge but not enough water to be excessively corrosive, and contaminating organic material.

'I'he reflux condensate from this rst fractiony ation is again subjected to fractional distillation in a second fractionating column at a somewhat higher temperature to decompose the alkyl iiuorides and to remove'another relatively dry hydrogen fluoride fraction together with some Vhydrocarbons from a second reflux condensate which will consist of a heavy organic liquid phase and a liquid phase containing hydrogen fluoride and water; either the constant boiling mixture ora mixture containing a higher lproportion of hydrogen fluoride than the constant boiling mixture One dilculty involved in the above describedl catalyst regeneration processes is in controlling the i'ractlal distillation so that themore corrosive comtant boiling mixture of hydrogen fluoride and water does not accumulate in any part of the apparatus where it would be harmful. In the apparatus shown in the drawing, any danger of the constant boiling mixture accumulating in the first regeneration column is eliminated by maintaining the top temperature of the fractionator suiliciently high to insure that the water is carried overhead. A constant boiling mixture vaporizes at approximately 235 F. at atmospheric pressure, and at higher temperatures with elevated pressures.

The second catalyst regeneration fractiona r shown in the drawing will ordinarily be quite ll and can be built oi' materials that will withstand the corrosive eects ofhydrogen fiuoride-water mixtures which accumulate and are withdrawn as reflux condensate.

The `preferred range of operating conditions which may be employed in an apparatus such as illustrated and above described for conducting the processes of the invention, may be approximately as follows: y

The pressure at the outletoi' the charge pump 't and in the reaction zone may be from 125 to 200 pounds per square inch. It is only necessary to use enough pressure to maintain both catalyst and hydrocarbonin the liquid phase. The temperature in the reaction zone may be in the neighborhood `of 100fto 125 F.. although the reaction will occur at temperatures 'below 0 `F'.

oride catalyst and the hydrocarbon charge, deilned as the volume of catalyst in the reaction zone divided by the volume per minute. of' hy-l drocarbon feed to the.. reaction zone may be' from about 5 to about 80 minutes. Although the ratio oi hydrocarbon to hydrogen fluoride in the reaction `zone may. vary considerably, a suitable ratio will be in the range of 0.5 to 20 parts of hydrocarbon to l part of hydrogen fluoride. The ratio of isoparafinto olen in the reaction zone may also vary considerably depending *upon other conditions, but will ordinarilyl be in the range. 'of from 1 to l0 molecular proportionsrof isoparailin per one molecular proportion of olefin.

As a specic example of an operation of the process as it may be conducted in an apparatus such as illustrated and above described: The charging stock is a, refinery gas containing 33% isobutane, 31% of butylenes, andtherest essentially normal butane and small amounts of pro-v pane. It is under suillcient pressure to be a liquid as supplied to line I and is discharged from pump- 3 at a npressure oi 150 pounds per square inch,

`combined with an isobutane recycle fraction through line 5l and then an emulsion of hydrocarbons and hydrogen uoride through line i3,

and thetotal material is then passed through pump 8, after which the pressure is 190 pounds per square inch. Therefore, the pressure drop in the emulsion recirculation system ls about 40 pounds per square inch. The reacted material withdrawn through line I5 and valve I8 is separated into a hydrogen fluoride layer and a hydrocarbon layer and the hydrocarbon layer is pumped through line 23 -to fractionator 2li. In this fractionator, small amounts of propane and hydrogeniluoride are removed.` The reilux con- 1 densate is again fractionated in fractionator t@ to remove the unreacted isobutane which is recycled through line 5| and valve 52 tothe beginning 'of the process. The ratio of isobutane to oleilns in the charge is approximately 1to1. However, when therecycled isobutane is combined with the charge, the ratio of -isobutane -to olefins becomes approximately 5 to 1. bottom of fractionator tu, a product is withdrawn which contains 53% normal butane andi7% alkylated hydrocarbon. This material may be fractionated further by means not shown in the drawing, to remove butane and high boiling alkylate and the desired fraction may then be blended with isopentane and leaded or otherwise treated to produce a nished aviation gasoline. For the reactivation of .the used hydrogen fluoride catalyst the ratio of the volume of catalyst regenerated to alkylate produced is approximately l to 30. This is suihcient to maintain the activity of the catalyst. The difference in pressure between the suction and discharge of the recirculating pump Sis about 40 pounds per square inch and is sumcient to recirculate the emulsion through the `emulsion settler. The ilow through the emulsion-settler is normally controlled by valve 5l. The ,hydrogen fluoride layer is removed from emulsion settler through line t8 to the catalyst regeneration fractionator tu.'

This fractionatoris operated at a pressure of pounds per square inch, at a temperature sumciently -high` to decompose the contaminating compounds and to remove hydrogen uoride and water overhead. A portion of the hydrocarbon vapors is condensed and reiluxed to the top. of

. the 'fractionatorr Only small amounts of heavy polymers are withdrawn from the bottom oi' frac- From the tionator Sthroug'h line 68. The pressure in fractionator 60 is substantially the same as that at the outlet oi' pump 6. The amount of purified hydrogen `fluoride being sent to fractionator 12 'to remove the water present, depends upon the amount of water present in the charge.

Although the example given describes a process for alkylating isobutane with butylenes, the invention is not limited .to this process but may also be-applied to the alkylationof other lsoparaiiins such as isopentane with other olefins such as propylene or' pentenes.

I claim as my invention:

i. A process for reacting isoparafilns with oleilns to produce saturated branched chain hydrocarbons which comprises subjecting a hydrocarbon mixture containing substantial proportions of said isoparaillnsand said olefins tocontact oride catalyst, separating theconversion products ,from-the hydrogen fiuoridegsubjecting said conversion products to fractional distillation to remove light gases and dissolved hydrogen uoride,

-f withdrawing the alkylate as a reflux condensate,

condensing and returning vaporous hydrogen fluoride from said fractional distillation to the andfractionally distilling in a second fractionation zone a stream of used hydrogen fluoride whereby to separate organic material as reux condensate and purified hydrogen fluoride as a vapor, condensing and returning-'a' portion of the purified hydrogen fluoride. to --the reaction zone, subjecting another portion of the purified hydrogen uoride to fractional distillation in a third fractionation zone whereby to separate a mixture of water and hydrogen uoride as reflux condensate and substantially water-free hydrogen fluoride as a vapor andlcond'ensing and re contact under alkylating conditions with a hydrogen fluoride catalyst, separating the .hydrocarbon conversion products from the hydrogen fluoride, subjecting' said conversion products to a first fractional distillation to remove propane and fractionation zone whereby to separate a mixture of water and hydrogen fluoride as reflux condensate and substantially water-free hydrogen fluoride as a vapor, and condensing and returnunderalkylating conditions-with hydrogen fluiv separate a mixture of water and hydrogen iluoride.

' reaction zone, separating from the reaction zone distillation to separate hydrogen fluoride and'4 water as an overhead product from hydrocarbons, returning a portion offsaid overhead product to' dissolved hydrogen fluoride from a reflux condensate, condensing and returning the hydrogen j fluoride from said first fractional distillation to the reaction zone, subjecting said reflux condensate to a second fractional distiliationfwhereby to separate an isobutane fraction from a secy ond reflux condensate, withdrawing said second ing the substantially water-free hydrogen fluoride to the reaction zone.

3. In a process for reacting isoparamns with oleflns to produce saturated branched chain hydrocarbons in which a hydrocarbon mixture containing substantial proportions of said isoparafns and said volefins is subjected to alkylation conditions in the presence of a hydrogen fluoride catalyst, the improvement which comprises separating a stream of used hydrogen fluoride from the alkylation reaction -zone and subjecting it to afirst fractional'distillation whereby to separate organic material as reflux condensate and purifled hydrogen fluoride as a vapor, .condensing and returning one portion of the purified hydrogen fluoride to said reaction zone, subjecting 'a second portion of the puried 'hydrogen fiuoride to a second fractional distillation whereby to as reflux condensate and returning substantially water-free hydrogen fluoride to the reaction zone.'

containing hydrogen fluoride', hydrocarbons-and water, subjecting saidv used catalyst to fractional the alkyiating step, subjecting'another portion thereof to further fractional distillation to sep- I stream of used catalyst containing hydrogen fluoride, hydrocarbons and water, vaporizing hydrogen iluoride and water from said used catalyst and separating the vapors from residual hydrocarbone, condensing the commingled hydrogen fluoride and water vapors and returning a portion of the resultant condensate to the hydrocarbon conversion step, .fractionating another' portion of said condensate to separate relatively dry hydrogen fluoride therefrom and returning the latter 4to the hydrocarbon conversion step.

6. In the alkylation of isoparalns'with oleilns in the presence of a hydrogen fluoride catalyst, the method which comprises removing from the alkylating step a liquid stream of used catalyst containing hydrogen fluoride, hydrocarbons and water, vaporizing hydrogen fluoride and water from said used catalyst and separating the vapors from residual hydrocarbons,v condensing the commingled hydrogen fluoride and water vapors and returning a portion of the resultant condensate to the alh'lating step, fractionating another por'- tion of said condensate to separate relatively dry hydrogen fluoride therefrom and returning the latter to the alkylating ste JOI-IN O. IVERSON. 

